Feedback on wiki page http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478

[Mamta Satoor <ms...@gmail.com>]

Hi,

I have created a wiki page for DERBY-1478 : Add built in language based
ordering and like processing to Derby

The wiki page is located at
http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478 and
it includes the current design proposal along with line items. If anyone has
any comments, please let me know.

thanks,
Mamta

Re: Feedback on wiki page http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478

[Mamta Satoor <ms...@gmail.com>]

Rick, Dan had also brought up this point. Dan's comment from *
http://www.nabble.com/Collation-feature-discussion-p9526316.html*
"This approach means that CHAR(varchar_col, 20) behaves differently to CAST
(varchar_col AS CHAR(20)). Not sure if that's good or bad, but they might be
implemented today using the same code path. "

I think what you are proposing will be easier to implement and easier to
explain to the users and fits in the SQL spec model. I wasn't trying to
solve any paritcular scenario but was just trying to make CHAR work like
TRIM when a character string type was it's first parameter. If no objections
by the end of the day, then I will go ahead and change the wiki page for
CHAR/VARCHAR functions to have the same collation as current schema's
character set no matter what kind of parameter is passed to it.


On 4/3/07, Rick Hillegas <Ri...@sun.com> wrote:
>
> Hi Mamta,
>
> Thanks for describing this behavior on a tidy wiki page. Having all of
> this material collected in one place is great. I have a comment:
>
> 6)CHAR, VARCHAR functions do not look like they are defined in the SQL
> spec. But based on 5) above, the result character string type's
> collation can be considered same as the first argument's collation type
> if the first argument to CHAR/VARCHAR function is a character string
> type. If the first argument is not character string type, then the
> result character string of CHAR/VARCHAR will have the same collation as
> current schema's character set. The collation derivation will be implicit.
>
> I think the behavior would be easier to understand if it were uniform,
> that is, if the CHAR and VARCHAR operators always returned strings which
> had the collation of the current schema. I suspect you will find that
> this is easier to implement. I also think that this is the intention of
> the SQL Standard. Here is my reasoning:
>
> It seems to me that there is a default (implementation-defined)
> character set and collation for the whole database. That default can be
> overridden at the session, schema, and client-module levels. That is,
> once you know what database, session, schema, and client-module you are
> in, you know the default character set and collation for string
> datatypes mentioned by your SQL statements. This default can be
> explicitly overridden with a CAST or COLLATE clause. There are also
> explicit exceptions to this behavior for certain operators ( e.g., TRIM,
> UPPER, LOWER, SUBSTR). The default character set and collation apply
> unless the SQL Standard explicitly defines an exception or your
> statement explicitly overrides the default. The default character set
> and collation apply to the return types of the CHAR and VARCHAR
> operators because the SQL Standard does not carve out an explicit
> exception for these operators.
>
> Is there some problem that would be solved by adopting the non-uniform
> behavior proposed on the wiki page?
>
> Thanks,
> -Rick
>
> Mamta Satoor wrote:
> > Hi,
> >
> > I have created a wiki page for DERBY-1478 : Add built in language
> > based ordering and like processing to Derby
> >
> > The wiki page is located at
> > http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478and
> > it includes the current design proposal along with line items. If
> > anyone has any comments, please let me know.
> >
> > thanks,
> > Mamta
>
>

Re: Feedback on wiki page http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478

[Rick Hillegas <Ri...@Sun.COM>]

Hi Mamta,

Thanks for describing this behavior on a tidy wiki page. Having all of 
this material collected in one place is great. I have a comment:

6)CHAR, VARCHAR functions do not look like they are defined in the SQL 
spec. But based on 5) above, the result character string type's 
collation can be considered same as the first argument's collation type 
if the first argument to CHAR/VARCHAR function is a character string 
type. If the first argument is not character string type, then the 
result character string of CHAR/VARCHAR will have the same collation as 
current schema's character set. The collation derivation will be implicit.

I think the behavior would be easier to understand if it were uniform, 
that is, if the CHAR and VARCHAR operators always returned strings which 
had the collation of the current schema. I suspect you will find that 
this is easier to implement. I also think that this is the intention of 
the SQL Standard. Here is my reasoning:

It seems to me that there is a default (implementation-defined) 
character set and collation for the whole database. That default can be 
overridden at the session, schema, and client-module levels. That is, 
once you know what database, session, schema, and client-module you are 
in, you know the default character set and collation for string 
datatypes mentioned by your SQL statements. This default can be 
explicitly overridden with a CAST or COLLATE clause. There are also 
explicit exceptions to this behavior for certain operators (e.g., TRIM, 
UPPER, LOWER, SUBSTR). The default character set and collation apply 
unless the SQL Standard explicitly defines an exception or your 
statement explicitly overrides the default. The default character set 
and collation apply to the return types of the CHAR and VARCHAR 
operators because the SQL Standard does not carve out an explicit 
exception for these operators.

Is there some problem that would be solved by adopting the non-uniform 
behavior proposed on the wiki page?

Thanks,
-Rick

Mamta Satoor wrote:
> Hi,
>  
> I have created a wiki page for DERBY-1478 : Add built in language 
> based ordering and like processing to Derby
>  
> The wiki page is located at 
> http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478 and 
> it includes the current design proposal along with line items. If 
> anyone has any comments, please let me know.
>  
> thanks,
> Mamta

Re: Feedback on wiki page http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478

[Mamta Satoor <ms...@gmail.com>]

Thanks for your kind words, Narayanan. Truly appreciate it.

Mamta


On 4/2/07, V Narayanan <V....@sun.com> wrote:
>
> Excellent work of organizing everything so neatly. As much as I am a
> passive reader of the language related work I really appreciate your
> efforts in organizing the discussions.
>
> Narayanan
>
> Mamta Satoor wrote On 04/03/07 11:35,:
>
> > Hi,
> >
> > I have created a wiki page for DERBY-1478 : Add built in language
> > based ordering and like processing to Derby
> >
> > The wiki page is located at
> > http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478and
> > it includes the current design proposal along with line items. If
> > anyone has any comments, please let me know.
> >
> > thanks,
> > Mamta
>
>

Re: Feedback on wiki page http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478

[V Narayanan <V....@Sun.COM>]

Excellent work of organizing everything so neatly. As much as I am a 
passive reader of the language related work I really appreciate your 
efforts in organizing the discussions.

Narayanan

Mamta Satoor wrote On 04/03/07 11:35,:

> Hi,
>  
> I have created a wiki page for DERBY-1478 : Add built in language 
> based ordering and like processing to Derby
>  
> The wiki page is located at 
> http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478 and 
> it includes the current design proposal along with line items. If 
> anyone has any comments, please let me know.
>  
> thanks,
> Mamta